CHICAGO (CBS) -- Starbucks workers were back on the picket line in Chicago Sunday afternoon—as they continue a five-day strike Friday to protest lack of progress in contract negotiations with the company. Baristas at the store at 5964 N. Ridge Ave.

Get all the news you need in your inbox each morning. "We're calling on allies to join us at 3 "anchor" picket lines TODAY. Each day, we'll announce more locations," the union posted on social media.

The workers’ union warns the walkouts could spread to hundreds of cafes by Christmas Eve if Starbucks does not meet demands at the bargaining table.